Glad you got an answer!

My question is; Can I apply for the DCF in Frankfurt even though she is not a German, but a visa carrying resident of Germany? I have an unrestricted visa because I was married to a German and my fiancee is in Germany on a student visa which runs out at the end of June (another reason we are nervous).
You will have to wait until after the marriage to apply, and have all the appropriate marriage certificates, etc. We got that on the day of our marriage, not sure if other places take time to get that in hand after the wedding. Have you checked the timelines for DCF Germany? If she has to be out of Germany by the end of June, what will you do for an address to have papers delivered to, and how will she get to the Consulate for her interview? Our process was very quick - Feb. 6th for I-130 submission, April 3rd for Interview - not sure about Germany!
Are you working for a US company that you will continue to work for back in the US? If so, you may not need a co-sponsor. If you do need one, I would think getting the I-864 from your co-sponsor in early June would be pretty good timing. The I-864 is NOT submitted with the I-130, but in the packet of information reviewed by the Consulate. For the I-130, you will need to show that you are living together, but that wouldn't have to happen until after the marriage. Getting a joint bank account would be a good thing, it is good proof for the I-130....
Look through those docs and guides carefully, check out the Embassy website for details on I-130 processing - it should have a wealth of information for you!

Good Luck and keep us posted, this is an interesting situation!